Mars Polar Lander Heads To Red Planet

By DIANE AINSWORTH

After a stellar launch at 3:21 p.m. Eastern Standard Time on Sunday, Jan. 3,
NASA's Mars Polar Lander is now on its way to the south pole of Mars to
search for water ice beneath the edge of layered terrain in this uncharted
region of the planet.

The spacecraft was launched atop a Delta II-class launch vehicle identical
to the expendable rocket used to loft Mars Climate Orbiter into space on
Dec. 11, 1998. Hitchhiking aboard the diminutive spacecraft are two
grapefruit-sized microprobes designed to crash into Mars' surface and carry
out up to seven days of soil and water experiments as far as 1 meter (3
feet) below the Martian surface. The probes will ride silently to Mars,
mounted on the Polar Lander's cruise ring, before they are turned on and
deployed 10 minutes before the mothership touches down.

"The launch was incredible, just amazing, because the vehicle is just
sitting there one minute and then it's gone," said Kari Lewis, chief mission
engineer on the New Millennium Deep Space 2 microprobe mission. "There was a
low cloud cover, though, so we didn't see it for very long."

Sixty-six seconds after liftoff on a cloudy, blustery day at Cape Canaveral
Air Station, and the morning after a storm packing 38-mile-per-hour winds
had swept through Cocoa Beach, the Delta's four solid-rocket strap-on
boosters were jettisoned.

At 4:03 p.m. EST, Mars Polar Lander separated from the third stage. A set of
solar panels located on the spacecraft's outer cruise stage were deployed
shortly thereafter and pointed at the Sun. The lander's signal was acquired
at 4:19 p.m. EST over Canber ra, Australia, by a 34-meter-diameter
(112-foot) Deep Space Network antenna.

The spacecraft is in excellent health, the flight team reports, and
continues to show normal power and temperature levels and the proper
attitude control for telecommunications with Earth using its medium-gain
horn antenna.

Earlier in the week, the flight team was continuing to analyze data from
Mars Polar Lander's star camera, which had not yet been able to lock on to
the proper set of stars to establish its reference in space. The situation
became evident shortly after lau nch, as the lander was beginning to try to
locate stars to establish its proper orientation in space. Proper operation
of the star camera was initiated on Wednesday morning.

Mars Polar Lander's interplanetary cruise will take it more than 180 degrees
around the Sun in a Type 2 trajectory, allowing the spacecraft to target a
landing zone close to Mars' south pole at 73 degrees to 76 degrees south
latitude. The precise landing zone will be pinpointed in June or July, about
five months before landing, with the help of new images taken by Mars Global
Surveyor.

The spacecraft is scheduled to fire its thrusters in a trajectory correction
maneuver Jan. 18. That maneuver, designed to remove a targeting bias
intended to prevent the third stage of the Delta II rocket from following in
the lander's flight path and col liding with Mars, as well as any small
launch injection errors, is expected to take approximately five minutes to
execute.